CRT Electron Lifetime and Purity Measurement Updates Richie Diurba - - PowerPoint PPT Presentation

CRT Electron Lifetime and Purity Measurement Updates

Richie Diurba

diurb001@umn.edu

1/20

Progress since January Collaboration Meeting

• Based on comments from reviewers, the electron lifetime measurements were

worked on to look at a week of beam data-taking.

• Measurements were made of a rise in purity and of Qc/Qa.
• Throughout this data-taking τ > 10 ms

Quantifying Lifetime

• Lifetime as a function of time: Q(t) = Qoe−t/τlifetime
• Lifetime as a ratio of charge on the cathode and anode:

Qc Qa = Q(ttot drift) Q(0)

= e−ttot drift /τlifetime

1

• Purity as a function of lifetime at approx. 500 V/cm: N02 = 500 ppt ms

τ

2/20

Introduction to Measurement

Basics (the x-coordinate in the diagram is pointing in the negative direction)

• CRT did not come alive until end of October, 2018 (Approx. run 5759).
• Because of the beam triggering, CRT tracks that enter BL dominate. This means

we could not measure BR TPC.

3/20

CRT Reconstruction

Matching tracks

• Match to a TPC track by minimizing the displacement between the CRT hit to

the TPC track, if we extrapolate the TPC track onto the CRT hit’s position in Z.

• Good purity (>99.9% in MC)

Example of CRT reconstruction on a handful of strips on two US modules and two DS modules.

Getting hits for lifetime studies

• Collect matched track hits between 230 < z < 460 and 200 < y < 400
• Take hit integrals and correct them for time (thit − tcrt)
• Measure dQ/dx by taking the hit integral and dividing by the step length to the

next collection plane hit.

• Correct based on the electric field and histogram integral within 0.1 ms time bin.

4/20

Calibrating Hits for the Space Charge Effect

To calibrate the electric field’s SCE displacements, we do the following:

• csce =

dQ/dx(Enom) dQ/dx(Ecalib sce)

• dQcorr/dx = csce ∗ dQuncalib/dx

Electric field calibrated is found by taking the track point from the CRT track position and feeding that coordinate into Mike’s data driven map.

Correction coefficient

5/20

Improvements to the Analysis

• CRT analyzer code was optimized to maximize the amount of data processed.
• The Landau-Gauss fitter was tuned thanks to the help of Tingjun and Roberto.
• The amount of events per 100 us slice in time for measuring the MPV of dQ/dx

was increased from 100 hits to 1000 hits. This ensures stability but it did get rid

• f a day from beam data-taking.
• YZ corrections were taken out as we found issues plotting dQ/dx as a function of
• Z. We are investigating this.

Old electron lifetime fit (left) and current (right) for run 5759

6/20

Increase in Purity Observed First Week of November 2018

• All errors are statistical and are modulated on a run-by-run basis so each

measurement has a Chi2/dof approx. at 1.

Run 5759 (left) and run 5770 (right)

7/20

Increase in Purity Observed First Week of November 2018

Run 5773 (left) and run 5776 (right)

8/20

Increase in Purity Observed First Week of November 2018

• I also think you get the point so I will be skipping a few runs, see backup for the

rest.

Run 5833 (left) and run 5841 (right)

9/20

Electron Lifetime Measurements

• There was not enough data for 11/6/2018 to make a precise electron lifetime

measurement.

10/20

Electron Lifetime to Qc/Qa

• Qc

Qa = e− 2.3 ms

τ

• 2.3 ms value taken from cathode-anode crossing study by Ajib and Tianle.

Charge ratio from cathode to anode. This plot is included in the paper.

11/20

Translating to Impurity Concentration

From Craig Thorn (BNL) using data from Bakale.

12/20

Impurity Measurement

• NO2 = 500 ppt ms

τ

at approx. 500 V/cm electric field (C. Thorn, ”Catalogue of Liquid Argon properties”, MicroBooNE doc:412)

Impurity estimate for November 2018

13/20

November 2019 Runs

Since beam data-taking, I have not been able to see a run since a purity recovery from late October that does not have minimal to no electron attenuation.

Run 10374 lifetime measurement for BR with data-driven interpolated map (left) and Run 10374 BR with Ajib and Tianle’s Cathode-And-Anode map (right)

14/20

November 2019 Runs

Before, we use the hit integral from the ADC fitting. Jianming suggested maybe summing the ADC signal would give a more accurate, non-infinite lifetime. This was not observed.

Run 10374 lifetime measurement for BR with data-driven interpolated map (left) and Run 10374 BR with Ajib and Tianle’s Cathode-And-Anode map (right)

15/20

Conclusion

• A week of data was analyzed during a rise in purity. This analysis was included in

the electron lifetime portion of the paper.

• Lifetime was always τ > 10 ms
• Using Thorn’s interpretation of Bakale, contamination was measured to be

consistently below 50 ppt oxygen equivalent.

• Jianming and I are currently working on combining the CRT measurement with

the purity monitor measurement so we can calibrate purity monitor data given the HV differences between the two.

16/20

Backup Slides

17/20

More Electron Lifetime Measurement Plots

Run 5780 (left) and run 5796 (right)

18/20

More Electron Lifetime Measurement Plots

Run 5780 (left) and run 5796 (right)

19/20

More Electron Lifetime Measurement Plots

Run 5814 (left) and run 5824 (right)

20/20